UV map of texture problem

Hi,
I’m trying to import my meshes from blender into UE4.
I keep running into the same issue, and I cannot find out what’s going wrong.
The meshes that apear wring have a dark red hue over them.
Some other meshes do import the right way.

220243-redwall.jpg

I learned that it’s better to create the lightmap inside UE.
So I think the prolem might be in the UV map.
The UV map displays in red in de editor

Further I noticed that there is only one material slot. In other meshes there where 2.

220245-matialslots.jpg

When I build light there are no error messages, but the material does’t display right.
in 1 instance there was a problem with the material, that isn’t the case here.

Any help please. I’ve been searching for weeks,
Sandra